1. Field of the Invention
The invention is related to the general field of remediation of contaminated soil, and to the more specific field of devices and methods of remediating soil in situ at a contaminated site.
2. Description of Related Art
U.S. Pat. Nos. 5,631,160 and 5,830,752 issued to this inventor describe an apparatus and methods of in situ soil remediation using a trenching tool. While the trenching tool has proven to be effective, and is in fact preferred for treating contaminated areas in proximity to walls or structures that inhibit maneuvering, and in areas with deep contamination in narrow seams, the inventor has found that it would be desirable in some instances to have an apparatus capable of a higher volume rate of soil treatment. Those instances include large open areas of contaminated soil, such as areas of landfills where contaminated soil is piled in rows or lies close to the surface.
The invention is in an apparatus for high volume in-situ treatment of contaminated soil to extract contaminants. The apparatus is a mobile vehicle, preferably a tractor with a crawler undercarriage, with a boom of the type typically used as a chain trenching tool. Booms of this type house a mechanism for driving a cutting chain. The chain drive mechanism is usually coupled to a mechanical or hydrostatic drive at the head end of the boom, and at the tail end has an idler wheel with sprockets to engage the soil cutting chain. There are commercially available several types of excavator drums that can be attached to the idler wheel or its axle to extend the width of soil cutting far beyond the width of the cutting chain. This invention uses such drums with a width of at least 1 foot each to increase the volume of soil being churned and treated in-situ. The drums are preferably modified from the commercially available configuration to provide soil cutting teeth arranged both for clock-wise and counter clock-wise rotation, and oriented to provide vertical lifting of the soil rather than funneling toward a center conveyor.
In a preferred configuration, the cutting teeth may be oriented at an angle and location such that some of the teeth propel soil across the drums in a direction away from the cutting chain and others of the teeth propel soil across the drums toward the cutting chain. This opposed directions causes the soil to swirl or vortex. In one alternative, the drum having a plurality of discs arising from and concentric with the drum, and teeth are located on the side walls and front rim of the discs.
The invention may include a hood disposed over the cutting drums to define a remediation chamber above the drums. In operation, contaminated soil is churned and broken down and lifted under the hood to release contaminant vapors. The hood may have ports for injecting high temperature air into the soil when it is lifted into the hood to bake out volatile contaminants. The hood may also have nozzles to inject a chemical or biological remediation fluid into the soil. In a preferred embodiment, the hood has internal partitions that confine vapor released from the soil and any remediation fluid in the chamber around the cutting drums, and create a vapor recovery chamber outboard of the drums. A vacuum line into the recovery chambers pulls gases out of the remediation chamber into the recovery chambers and then to a filtration or other disposal device. The vehicle preferably has a hydraulic means to tilt the hood to match the terrain.